United States Nuclear Regulatory Commission - Protecting People and the Environment

EA-97-232 - Sequoyah 1 & 2 (Tennessee Valley Authority)

July 10, 1997

EA 97-232

Tennessee Valley Authority
ATTN: Mr. Oliver D. Kingsley, Jr.
President, TVA Nuclear and
Chief Nuclear Officer
6A Lookout Place
1101 Market Street
Chattanooga, TN 37402-2801

SUBJECT:  NOTICE OF VIOLATION 
          (NRC SPECIAL INSPECTION REPORT NOS. 50-327/97-05 AND 50-328/97-05)

Dear Mr. Kingsley:

This refers to the special inspection conducted on March 24 through May 22, 1997, at the Sequoyah facility. The purpose of the inspection was to review aspects of the Unit 1 reactor coolant system (RCS) inadvertent drain down which occurred on March 24, 1997. The results of the inspection were sent to you by letter dated May 27, 1997. An open, predecisional enforcement conference was conducted in the Region II office on June 27, 1997, with you and members of your staff, to discuss the apparent violations, the root causes, and corrective actions to preclude recurrence. A list of conference attendees and copies of the Nuclear Regulatory Commission's (NRC) and Tennessee Valley Authority's (TVA) presentation materials are enclosed.

Based on the information developed during the inspection and the information that was provided during the conference, the NRC has determined that violations of NRC requirements occurred. The violations are cited in the enclosed Notice of Violation (Notice), and the circumstances surrounding them are described in detail in the subject inspection report.

The RCS drain down event occurred during an evolution to reduce pressurizer level to 25%, following plant shutdown. You stated that the evolution included a rapid RCS depressurization which caused voids in the reference leg for the cold calibrated pressurizer level instrument and erroneous indication of pressurizer level in the control room. Operators relied on the erroneous indication and inadvertently drained the pressurizer and subsequently the RCS to a level just below the top of the reactor vessel head.

Two violations were identified as a result of the event. Violation A involved two examples of the failure to identify and take adequate corrective actions for a significant condition adverse to quality. In the first example of Violation A, TVA failed to identify and correct deficiencies in the control of RCS inventory during a reduction of pressurizer level. The root cause of this example of the violation was the failure of TVA management to provide the proper combination of operator training and procedural guidance necessary to identify the discrepancy in the pressurizer level indication. As a result, although the operators appeared to be attentive to their duties and were monitoring the hot calibrated and cold calibrated pressurizer level instruments, they failed to identify a malfunction of the cold calibrated pressurizer level instrument. It is also of particular significance that although the operators questioned the conflicting indications including receiving and acknowledging alarms in the control room indicating letdown isolation and low pressurizer level, they failed to stop the evolution promptly and determine if further actions were necessary to effectively analyze the conflicting level indications. The operators continued the pressurizer drain down until a reactor operator, assuming shift duties after a shift change, noted the discrepancy between pressurizer level and a reactor vessel level indication and initiated corrective actions. A weakness was also noted in implementation of corrective actions for a loss of RCS inventory control in 1993. TVA had determined that procedural controls for RCS inventory control should be enhanced, based on a previous event review for a 1993 Sequoyah Unit 1 inadvertent RCS drain down. These controls included measures to ensure (1) positive inventory control, (2) use of a pressurizer level correction curve which showed the relationship between the hot and cold calibrated instruments, and (3) use of multiple independent channels to confirm the accuracy of instruments relied on during the drain down. However, the corrective action for the 1993 event focused on precluding inventory control events only at low pressurizer levels and the procedure for operation in normal pressurizer level bands was not revised.

In the second example of Violation A, TVA failed to identify that two previous backfills of the pressurizer level instrument reference legs that occurred after rapid RCS depressurization evolutions were evidence of the pressurizer level instrument's susceptibility to voiding during rapid RCS depressurization. As a result, corrective actions were not taken to ensure that adequate indication of RCS inventory was available during reductions in RCS inventory.

Violation B involved failures to log correctly and accurately the plant's status as required by plant operating procedures.

The NRC is concerned that, when faced with the discrepant indications, the operators failed to take immediate corrective actions to determine actual RCS inventory. The operators also failed to take precautionary steps, such as consulting the pressurizer level correction curve which was available in the control room, or implementing positive inventory controls prior to commencing the RCS drain down evolution. In addition, the NRC is concerned that previous opportunities to identify the level instrument failure mode were lost when you failed to evaluate the circumstances surrounding two previous cold calibrated reference leg backfills due to voiding in the pressurizer level reference leg.

The March 1997 Unit 1 RCS drain down event is also of particular concern to the NRC because of the similarity of this event to the 1993 Unit 1 RCS drain down. Although, the actual safety consequences of both events were low, the recurrence of this event, as a result of operator errors and failure to provide adequate procedural or training guidance, represents a significant regulatory concern. In light of the potential consequences of the loss of reactor coolant inventory, licensees should take aggressive action to ensure that appropriate procedures and training are provided to ensure that RCS inventory is effectively controlled, particularly during evolutions involving planned reductions in RCS inventory. Additionally, corrective action effectiveness has been an ongoing concern at Sequoyah. Therefore, the violations have been categorized in the aggregate in accordance with the "General Statement of Policy and Procedures for NRC Enforcement Actions" (Enforcement Policy), NUREG-1600, as a Severity Level III problem.

In accordance with the Enforcement Policy, a base civil penalty in the amount of $55,000 is considered for a Severity Level III problem occurring after November 12, 1996. Because your facility has been the subject of escalated enforcement actions within the last two years,1 the NRC considered whether credit was warranted for Identification and Corrective Action in accordance with the civil penalty assessment process described in Section VI.B.2 of the Enforcement Policy. NRC determined that credit was warranted for Identification in that the violations were identified by your staff. At the conference, your staff stated that corrective actions taken or initiated included the following: (1) reinforce management expectations of Operations personnel; (2) revision of the general operating procedure to control backfill of the cold calibration level channel reference leg, ensure use of multiple level indications during drain down and ensure positive inventory controls; (3) enhanced training and evaluation of crew performance; (4) self-assessment of Operations including an independent assessment conducted by peers from other operating plants. Based on the above, the NRC determined that the corrective actions appeared to be comprehensive and that credit was warranted for the factor of Corrective Action.

Therefore, to encourage prompt identification and comprehensive corrective actions for violations, I have been authorized, after consultation with the Director, Office of Enforcement, not to propose a civil penalty in this case. However, significant or further repetitive violations in the future could result in a civil penalty.

You are required to respond to this letter and should follow the instructions specified in the enclosed Notice when preparing your response. In your response, you should document the specific actions taken and any additional actions you plan to prevent recurrence of the violation. After reviewing your response to this Notice, including your proposed corrective actions and the results of future inspections, the NRC will determine whether further NRC enforcement action is necessary to ensure compliance with NRC regulatory requirements.

In accordance with 10 CFR 2.790 of the NRC's "Rules of Practice," a copy of this letter and its enclosure will be placed in the NRC Public Document Room.

                             Sincerely, 

                             Original signed by 
                             Bruce S. Mallett for

                             Luis A. Reyes,
                             Regional Administrator

Docket Nos. 50-327, 50-328
License Nos. DPR-77, DPR-79

Enclosures:
1. Notice of Violation
2. NRC Presentation Materials
3. TVA Presentation Materials
4. List of Attendees

cc w/encls:
O. J. Zeringue, Senior Vice President
Nuclear Operations
Tennessee Valley Authority
6A Lookout Place
1101 Market Street
Chattanooga, TN 37402-2801

Jack A. Bailey, Vice President
Engineering & Technical Services
Tennessee Valley Authority
6A Lookout Place
1101 Market Street
Chattanooga, TN 37402-2801

M. Bajestani
Site Vice President
Sequoyah Nuclear Plant
Tennessee Valley Authority
P. O. Box 2000
Soddy-Daisy, TN 37379

General Counsel
Tennessee Valley Authority
ET 10H
400 West Summit Hill Drive
Knoxville, TN 37902

Raul R. Baron, General Manager
Nuclear Assurance and Licensing
Tennessee Valley Authority
4J Blue Ridge
1101 Market Street
Chattanooga, TN 37402-2801

Pedro Salas, Manager
Licensing and Industry Affairs
Tennessee Valley Authority
4J Blue Ridge
1101 Market Street
Chattanooga, TN 37402-2801

Ralph H. Shell, Manager
Licensing and Industry Affairs
Sequoyah Nuclear Plant
P. O. Box 2000
Soddy-Daisy, TN 37379

J. T. Herron, Plant Manager
Sequoyah Nuclear Plant
Tennessee Valley Authority
P. O. Box 2000
Soddy Daisy, TN 37379

Michael H. Mobley, Director
Division of Radiological Health
3rd Floor, L and C Annex
401 Church Street
Nashville, TN 37243-1532

County Executive
Hamilton County Courthouse
Chattanooga, TN 37402


NOTICE OF VIOLATION

Tennessee Valley Authority                      Docket Nos. 50-327 and 50-328
Sequoyah Units 1 & 2                            License Nos. DPR-77 and DPR-79
                                                EA 97-232

During an NRC inspection conducted from March 24 through May 22, 1997, violations of NRC requirements were identified. In accordance with the "General Statement of Policy and Procedure for NRC Enforcement Actions," NUREG-1600, the violations are listed below:

A. 10 CFR 50, Appendix B, Criterion XVI, requires, in part, that measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances, are promptly identified and corrected. In the case of significant conditions adverse to quality, the measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition.

Contrary to the above, the licensee failed to establish measures to assure that a significant condition adverse to quality was promptly identified and corrected and corrective action was taken to preclude repetition. Specifically,

1. On March 23 and March 24, 1997, during an evolution to drain the pressurizer to 25% level, the licensee failed to identify the inability to accurately monitor and control reactor coolant system (RCS) inventory, a significant condition adverse to quality. Specifically, several operations personnel observed a malfunction of the cold calibrated pressurizer level instrumentation and failed to promptly identify that the pressurizer cold calibration level indication was malfunctioning and take corrective action. This unidentified malfunction contributed to the inadvertent draining of the pressurizer to less than 0% cold calibration level.
2. On September 11, 1995, and on April 24, 1996, the cold calibration reference legs for Unit 1 and Unit 2, respectively, were backfilled after rapid depressurization of the RCS, and the licensee failed to take measures to ensure that RCS inventory could be properly monitored and controlled in that the cause of the reference leg voiding was not identified and corrective actions to preclude repetition of the reference leg voiding were not taken. (01013)

B. Technical Specification 6.8.1.a requires, in part, that procedures shall be established, implemented, and maintained covering the activities recommended in Appendix A of Regulatory Guide 1.33, Revision 2, February 1978, "Quality Assurance Program Requirements (Operation)." Appendix A of Regulatory Guide 1.33, Section 1, includes procedures for "Log Entries, Record Retention, and Review Procedures."

SSP-12.1, Conduct of Operations, Revision 16, Section 3.8.3 C. 3. requires, in part, that relevant information reflecting static or changing plant conditions shall be recorded in at least one narrative log. Section 3.8.5 D. requires, in part, that late entries shall be annotated by placing the current time and the words "LATE ENTRY", followed by the time the entry should have been made, and then the entry.

Contrary to the above, on March 23 and 24, 1997, relevant information reflecting static or changing plant conditions was not recorded in at least one narrative log, in that: (1) on March 23, a Unit 1 RCS drain down was initiated at approximately 11:00 p.m. and was not recorded; (2) on March 24, a Unit 1 RCS drain down was terminated at approximately 2:00 a.m. and was not recorded; and (3) on March 24, 1997, a Unit 1 RCS drain down was logged at 8:25 a.m. as being initiated at approximately 7:15 a.m. and terminated at approximately 7:45 a.m., and the log entry was not annotated as a "LATE ENTRY." (01023)

These violations represent a Severity Level III problem (Supplement I).

Pursuant to the provisions of 10 CFR 2.201, Tennessee Valley Authority (Licensee) is required to submit a written statement or explanation to the U. S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, D. C. 20555 with a copy to the Regional Administrator, Region II, and a copy to the NRC Resident Inspector at the Sequoyah facility, within 30 days of the date of the letter transmitting this Notice of Violation (Notice). This reply should be clearly marked as a "Reply to Notice of Violation" and should include: (1) the reason for the violation, or, if contested, the basis for disputing the violation, (2) the corrective steps that have been taken and the results achieved, (3) the corrective steps that will be taken to avoid further violations, and (4) the date when full compliance will be achieved. Your response may reference or include previously docketed correspondence, if the correspondence adequately addresses the required response. If an adequate reply is not received within the time specified in this Notice, an order or Demand for Information may be issued as to why the license should not be modified, suspended, or revoked, or why such other action as may be proper should not be taken. Where good cause is shown, consideration will be given to extending the response time.

Under the authority of Section 182 of the Act, 42 U.S.C. 2232, this response shall be submitted under oath or affirmation.

Because your response will be placed in the NRC Public Document Room (PDR), to the extent possible, it should not include any personal privacy, proprietary, or safeguards information so that it can be placed in the PDR without redaction. If personal privacy or proprietary information is necessary to provide an acceptable response, then please provide a bracketed copy of your response that identifies the information that should be protected and a redacted copy of your response that deletes such information. If you request withholding of such material, you must specifically identify the portions of your response that you seek to have withheld and provide in detail the bases for your claim of withholding (e.g., explain why the disclosure of information will create an unwarranted invasion of personal privacy or provide the information required by 10 CFR 2.790(b) to support a request for withholding confidential commercial or financial information). If safeguards information is necessary to provide an acceptable response, please provide the level of protection described in 10 CFR 73.21.

Dated at Atlanta, Georgia
this 10th day of July 1997


1. Two Severity Level III problems and proposed civil penalties of $50,000 each were issued on December 24, 1996, (EA 96-414) for inadequate corrective actions related to maintenance of reactor trip breakers and other equipment. A Severity Level III violation and proposed civil penalty of $50,000 was issued on November 19, 1996, (EA 95-269) related to fire protection program deficiencies. A Severity Level II violation and proposed civil penalty of $80,000 were issued on February 20, 1996, (EA 95-252) related to employee discrimination in Department of Labor Case Nos. 92-ERA-19 and 92-ERA-34.

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